This will probably be a long and boring answer for some but I will try to help folks understand the terms High and Low pressure.

High pressure systems are usually above 1/2 PSI and up to 30 PSI as found in most of the portable cookers and fryers. This is an easy and cheap way to go for the makers of the cookers as the higher the gas pressure the greater the heat delivery for a given size burner. The common heating system gas valves are not usable at these pressures and there are no conversion parts to make them safely operate at greater than 1/2 PSI. The main option for safe burner operation at high pressure is to use 2 solenoid valves per burner and an electric ignition control module that lights pilot burner and turns off gas if pilot goes out to prevent explosion.

Low pressure systems have 2 pressure standards in use, 11" WC(water column) for propane systems, and 4" WC for residential Natural Gas systems. The gas furnace valves with standing pilots can be used on brew rigs for burner control instead of 2 solenoid valves with ignition module, and the cost is usually only 25% more than a single solenoid valve. For those that want the bling factor of electric ignition there are suitable gas furnace valves and igntion modules, or the 2 solenoid valves, 1 ignition module method.

Most of the gas burners popular in homebrewing can be operated at either high or low pressure if the correct gas jet is used, as stated before more pressure gives more fire with same size burner. While the multijet burners have their uses you need to know that the multijet burners are only happy at or near wide open and are sometimes used under the HLT. The 10" Banjo/Hurricane burners are able to operate over a wide range of settings and are usually used where flame adjustment is important like MLT and boil kettle applications.

Solenoids for burner control should be able to operate from 0 - 100 PSI as the solenoids that operate at 5 PSI - 100 PSI require at least 5 PSI pressure just to open, if used on low pressure they will not work. The popular solenoid valves in use on the brew rigs are the STC 2W160's as they are more reasonably priced than the equivalent ASCO valves. If you are going the solenoid valves and ignition module control route, the solenoids need to have coils built for 24 VAC to work with the ignition module.

wow, $7.99 for a burner. haven't seem them that cheap before. 170,000 btu's is an awful lot. Do you see any scorching with them? I know the BG-14 on the website shows the 10" diameter 100,000 btu unit. thought that might be better. Lonnie Mac uses the 10 tip jet burners, and that's what i was originally thinking. i am using 3 keggles in my set up.

any places to buy everything i need to rig up a pilot for MLT and HLT?

The low pressure burner route will be a bit easier to build and the cost per burner will be about $100 for parts and 10" Banjo burners. If you have time and are willing to endure the auction sites you could save some money if not then here are a couple places to shop, burners AG supply, gas valve, pilot burner and thermocouple-PEX Supply.
PEX supply,
Gas valve part number Honeywell VR8300A3500
Pilot burner Q314A4586
thermocouple Q390A1061
Can be found at RV supply sites:
Low pressure LP regulator Marshall 299-00
Burners
AG supply BG-14 High Pressure Cast Iron Burner (will work well on low pressure) if gas jet is drilled out for low pressure LP

does this part replace the asco valves? this is the part of the build that is going to complicate me the most

Yes the Honeywell valves will replace the ASCO valves in the gas system, piping will be essentially the same. There are some examples posted of Brutus systems with Honeywell gas valve controls to look at for reference if needed and if you need help in burner jet conversion there are replacement gas jets for low pressure available or you can drill out the high pressure ones that come with the burners.